Power factor correction is often used in electric power systems and between power sources and loads in order to synchronize the input current and the input voltage before it is delivered to the load. Power factor correction can provide many benefits to the electric power system and the load, such as prolonged life and energy efficiency.
Traditionally, power factor correction circuitry is designed as voltage-based power factor correction. Such circuitry is used in constant voltage systems, and the input current waveform is made to match the input voltage waveform. Additionally, standard digital power factor correction methods utilize a 60 hertz sine wave as a reference to match the waveform of the input current to the input voltage. However, in certain industries, such as airfield lighting, the existing infrastructure requires current based systems which require a constant current power source rather than a constant voltage power source. Specifically, in the area of airfield lighting, constant current systems are traditionally used because of the need for consistent brightness across the plurality of light fixtures coupled in series and being powered by the same power source. Because a constant current power supply can provide the same level of current to each of the light fixtures, it became the standard form of power distribution in the area of airfield lighting. Though lighting technology has become more sophisticated, the infrastructure has remained a current based system. However, power factor correction techniques used for voltage based systems which receive a constant voltage generally cannot be used for current based systems. Furthermore, in airfield lighting systems and other constant current or constant voltage systems, many power sources do not supply a true sine wave input. For example, series-switch regulators used in airfield lighting are non-sinusoidal power sources. Other examples include emergency generators which may produce a sine wave, but at a varying frequency, and certain power inverters may produce square waveforms. However, traditional sine-based power factor correction requires the input waveform to be substantially similar to a sine wave for good power factor correction. The same challenge exists for power factor correction of constant-voltage systems when the input voltage is not a regular sinusoidal waveform. Thus, power factor correction of non-sinusoidal constant voltage or constant current inputs using the traditional sine-based method is limited or less efficient.